Process for the manufacture of aluminum



Patented July 2, 940. I 2 20 552 UNITED STATES PATENT, OFFICE PROCESS FOR THE MANUFACTURE or ALUMINUM Henri Louis Gentil, Paris, France, assignor to Socit dElectrochimie, dElectrometallurgie et des Acierics Electriques dUgine, Paris, France, a corporation of France No Drawing. Application January 3, 1939, Serial No. 249,150. In France January 11, 1938 8 Claims. (.01. 75-68) The well known process of manufacturing alualuminum contained in the ore it forms sulphurminum by electrolytically treating bauxite, shows ous anhydride (S02) which can be collected and several disadvantages: which is a valuable product. Calcium sulfide is (a) The bauxite "must undergo a preliminary also a good reducer to be used in the process transformation; but it is more expensive than iron-sulfide. 5 I (b) The process is a costly one because it ne- Under the action of the high heat and of the cessitates a pure alumina to be first prepared; far reaching vacuum the reducing agent reduces (c) The metal obtained contains no more than the oxygenated aluminum compounds of the ore 99.5% of pure aluminum. 4 to which the reducing agent has been mixed, by.

1!) By the present invention which discards all liberating aluminum which is volatilised and 10 these disadvantages, a metal containing up to later on condensed. 99.95% of pure aluminum is obtained with a low It is preferable to finely grind the ore and the cost and a high yield. reducingagent, to thoroughly intermix them and This invention principally consists in directly finally to mould the mixture into briquettes ac- 1 treating, at a temperature above the volatilising cording to a process well known in the art and temperature of the aluminum and under a high to submit these briquettes under vacuo to the vacuum, i. e. an ore containing an oxydised comaction of a high heat. pound of aluminum, an aluminous ore. such e. g When e. g. operating by treating at 1600 C. as bauxite, volcanic cinders, clay, even when poor under a vacuum of 2-3 mm. of mercury, by

in aluminum, by a reducin a en pable of remeans of iron-sulphide obtained for instance 20 ducing at the high temperature, of the process. from iron-pyrites, a low grade bauxite containthe said aluminous oxygenated compounds of ing: l

the ore. '1 A suitable temperature for the operation is I gfi 1800 C. although already good results may be 1 0 .3 0 42 25 obtained at a temperature of about 1200 C. SiO Nevertheless the temperature. should not be so Fezoas s r s 58 high that owing to the value of the vacuum which 2-- has been chosen other metals are liberated by Impuntles 80 a reduction reaction and are volatilized which the iron sulphide directly reduces the alumina 80 are condenslble at the condensing temperature of contained in the bauxite; the iron and e aluminum and are soluble in aluminum or are phur re e tively bin with the oxygen of the miscible therewith. The higher the vacuum the alumina by f in iron oxyde (F8202) and lower is the temperature at which the process can phurous anhydride (S02) and aluminum is be performed, and vice versa.

On theother hand a vacuum of 2-10 mm. of mercury gives especially advantageous results at the temperatures above referred to. Thus a temformed. The aluminum is volatilised and is collected by .a condensation process. The sulphur- Derature of 1200 C. is convenient for the process gg zg gg s ig t ggggj .iig g fig f ig 4 when the vacuum reaches 2 of mercury 1 obtained contains 99 .95% of pure aluminum and reducing z g g of ggf the yield is 90% of the aluminum contained in e auminouscompoun 5 un er e con 1 ions quoted above may be used for carrying out-the g g excess i q relatwely invention, provided they are cheap. Metallic e i con e ore sulphides are particularly advantageous and used because m of h reducmg especially halfqaw sulfides as Obtained by sepa agent is consumed for performing by-reactions rating from naturalmetallic sulfides the gangue notably for the formanon of the v and the exterior impurities, i. e. the earthy or fides,above referred Generally the sand organic parts which may be adheringto the ore. 088,5 of about 10% of theIweight of 191160 Iron sulfide is especially suitable because of its 'rencal quantityv strong reducing power, its low cost, the shape Thus it appears that wlthout any preliminary under which it i's sold, the eas'iness of eventually transformation of t u and Without the drying it and splitting it in pieces and grinding p p a n f a v y pu a um na a hi hly it and finally because when being itself oxydised pure aluminum is obtained by one operation only at the expense of the oxydised compounds of the (concomitant reduction, volatilisation and con- 5 erated. Complex sulfldes are simultaneously ing materials or the products obtained. Known 1 electrically heated furnaces having an aluminous lining (e. g. silimanite or corundum) may be used for the purpose. Any other equivalent heating means other than electricity could also be used.

I'claim:

1. A process for the manufacture of very pure aluminum consisting of directly treating an'aluminum ore containing an oxygenated aluminum compound, under a far reaching vacuum and at a high temperature, by a metallic sulphide capable of reducing the said oxygenated aluminum compound at a temperature above the temperature of volatilization of aluminum and condensing the aluminum vapours evolved.

2. A process -for the manufacture of very pure aluminum, consisting of directly treating an aluminum ore containing an oxygenated aluminum compound, under a far reaching vacuum and ,at a high temperature, by a metallic sulfide capable of reducing the said oxygenated aluminum compound at a temperature above the temperature of volatilization of aluminum and condensing the aluminum vapours evolved.

3. A process for the manufacture of very pure aluminum, consisting of directly treating by iron sulfide an aluminum ore containing an oxygenated aluminum compound under a far reaching vacuum and at a high temperature and condensing the aluminum vapours evolved.

4. A process for the manufacture of very pure aluminum, consisting of directly treating by caltemperature and condensing the aluminum vapours evolved.

6. A. process for the manufacture of very pure aluminum, consisting of directly treating an aluminum ore containing an oxygenated aluminum compound under a vacuum of about 2 mm of mercury and at high temperature by a metallic sulphide at a temperature above the temperature of volatilization of aluminum and condensing the aluminum vapours evolved. f

7. A process for the manufacture of very pure aluminum consisting of directly treating by a metallic sulfide an aluminum ore containing alumina, under a far reaching vacuum and at a high temperature above the volatilizatlon temperature of aluminum and condensing the aluminum vapours evolved.

8. A process for the manufacture of a very pure aluminum, consisting of directly treating by a metallic sulfide an aluminum ore containing alumina, under a far reaching vacuum and at a high temperature above the volatilization temperature of aluminum and condensing the aluminum vapours evolved and separating the sulfurous anhydride produced.

HENRY poms -GEN'IIL. 

